Suggestions about captive portal

Hi all, I would like to know what Captive Portal you advise to use and in particular what supports better Freeradius. For the moment I'am using Chillispot. My problem is always the same: set the NAS to accept the IP address, assigned by IP pool, from FreeRADIUS. I have searched documentation related to my NAS (Doc, forum, mailing list, ecc.ecc.) but I haven't find nothing of useful for my problem. Fort this reason i would to use another captive portal (that support freeradius) that can solve my problem. Thanks in advance for every advice or help. Best regards. Giusy